In deep oil well production it is necessary to pump the natural oil from within the earth to the surface. In one method, an eccentric worm pump is located in the borehole at the desired depth and the drive and motor are located on the surface. Drives for eccentric worm pumps for the transportation of liquids in the natural oil conveying industry are known, in which a motor drives a pump down in a well by means of deep well pump rods at a speed which is constant, can be switched in phases or infinitely (e.g., electrically, mechanically or hydrostatically controlled) via a step-down gear all of which is positioned above ground. The deep well pump rods, however, are long, heavy, expensive and power-consuming rods. Such drives and the rods also are unsuited for use with deviated wells. Further, such drives cannot be adapted for use at the bottom of the well or in the borehole due to their large dimensions.
Attempts have been made to develop a gearbox assembly that can be co-located in the borehole along with the pump and motor. However, these gearboxes were unable to sustain operational capability for long periods of time under the severe environmental conditions, high temperatures on the order of 120-130.degree. C. (250-270.degree. F.) and high pressures on the order of 40-50 atmospheres. Such gearbox assemblies also proved to be very complex and employed multiple lubrication systems.
It thus would be desirable to provide a gearbox that can resist the environmental conditions that exist with deep oil wells, that would develop high torque and which would be small in cross section so it could be located with the pump and motor in the well borehole. It would be particularly desirable to provide such a gearbox that would be capable of withstanding the high axial loads developed by the head of pumped oil. It also would be desirable to provide such a gearbox that would operate for long time periods and include an improved lubrication system that would ensure adequate lubrication and cooling of rotating and bearing components of the gearbox when located in a borehole in comparison to prior art devices.